This invention relates to devices whereby hand motions are converted into continuously variable electrical signals to provide an interface between man and machine. More specifically, this invention relates to phase-sensitive devices in which the location of an operator's finger in the field of a specially constructed plane is determined in one or more axes by the phase of a signal frequency or frequencies relative to the phase of a reference frequency or frequencies.
Presently used electrical control devices of the continuously variable kind involve projecting knobs, handwheels, levers or joysticks. Electrical telewriting generators use a pen or stylus of some kind. Manual input devices that perform analogous functions in data processing systems usually use light pens. A phase-sensitive system described by A. B. E. Ellis in U.S. Pat. No. 3,530,241 uses a capacitively coupled probe that must be held by the operator. All these devices, which produce electrical signals that corresond to hand motions of an operator, require that something be grasped and manipulated by the operator.
My invention eliminates the requirement for grasping and manipulating, permitting a more direct and convenient interface with a machine. In particular, it allows natural and convenient two-axis motions without the mental translation required to use two separate knobs or levers. Additionally, it permits such devices to be constructed without projecting knobs or levers, giving such practical benefits as preventing injury by collision with said knobs or levers, enhancing the esthetic appeal of products by making the controls an integral part of the surfaces of the products, and protecting devices used by the public, such as electronic games, from misuse or vandalism by eliminating projections that can be broken or twisted off. A further advantage is that a "dead-man" feature can conveniently be made part of the device, preventing operation of equipment unless the operator is in the correct position.